Annunciator system with mobile receivers

ABSTRACT

A system for annunciating traffic information includes a plurality of stationary transmitters (42,46) for generating relatively short range, highly directional beam signals (44,48) containing a burst data stream signal (10) to each of a plurality of mobile receivers (50,52,54). The stationary transmitter (42) includes a transmitter (42a) connected to a transmitter antenna (56) for generating the beam signal (44) and to a transmitter control (60) which is connected to a transmitter memory (68) for storing a plurality of compressed data voice messages which are read by the transmitter control and generated as data packet signals (16,20,22) in the burst data stream signal (10). The mobile receiver (54) includes a receiver antenna (58) for receiving the beam signal (44), a receiver (54a) for separating the burst data stream signal (10) from the beam signal, a receiver control (70) for reading the data packet signals, a data decompression circuit (72) for decompressing the data packet signals and an audio playback device (78) for audibly reproducing the messages. A traffic signal (36) connected to the transmitter control (60) generates traffic signal state signals which are generated as status flag signals (14,28) in the burst data stream signal (10) and the receiver control (70) responds to the status flag signals by generating a traffic signal state indication from an output device (80).

BACKGROUND OF THE INVENTION

The present invention relates generally to an apparatus for transmittinginformation to mobile receivers and, in particular, to an apparatus forannunciating traffic information.

Radio traffic advisory systems have been used for many years to alertdrivers to special attractions or warn drivers of traffic problems.Short range AM or FM transmitters are used in state and national parksto inform visitors of certain features or to broadcast specialdirectives.

Generally, the messages are fairly long and may be heard on certainbroadcast band radio stations (the frequencies of which are posted onroadside signs). The operational range of these highway informationsystems is such that any vehicle in the general vicinity of thetransmitting antenna is able to receive the broadcast irrespective ofthe direction of travel. That is, the broadcast is essentiallyomnidirectional.

There is a great need for annunciator systems, for highway use inparticular, that are very site specific and direction specific. Forexample, at a given intersection a certain traffic message may beappropriate for Northbound traffic, but not appropriate for travelers inother directions. Furthermore, announcements at given intersections maybe inappropriate at intersections only a few hundred feet away. Suchsite specificity is particularly important in densely populated urbanareas.

Traditional broadcast band (AM or FM) frequencies are not very usefulfor such short range, highly directional use because practical antennasfor these bands are not narrowly directive. Microwave or infraredcarrier frequencies are more useful for such purposes, and can be madehighly directional. At radio frequencies above 10 GHz, and in theinfrared spectrum, radiation behaves similar to visible light, and canbe conveniently focused or directed with simple, compact antennastructures. Reflectors, lenses and similar hardware can be used toconfine the transmission and reception of these wavelengths to veryspecific areas. Relatively low radiated power from the transmitterlimits the range so that frequency reuse is practical several hundredmeters or even tens of meters away.

Certainly the technology for such short range links is clearly in place,and in fact some experimental roadside signpost systems use short rangetransmission to send digital position data to vehicular receivers. Suchon-board navigation schemes rely on periodic positional updating formaintaining absolute accuracy of dead reckoning navigation engines.However, digital maps and moving cursors are notoriously intrusive, andthere is some evidence that the safety of the driver and passengers maybecome an issue if moving maps or alpha numeric displays becomecommonplace.

An ideal annunciator system would use audio messaging as is used inlocal radio advisory systems, but with distinct area and directionspecificity. The problem with adapting short range microwave or infraredtransmission to deliver specific voice messages is that the receivermust stay in range of the transmitter for the duration of the broadcastmessage or messages. In real terms, such an arrangement is impracticalbecause in all but the slowest moving traffic, the residence time of themobile receivers would be too short to receive a reasonable message.That is, the mobile receiver would be in range of a particulartransmitter for only seconds if the vehicle was moving anywhere close totypical speeds.

SUMMARY OF THE INVENTION

The present invention concerns an apparatus for annunciating informationto mobile receivers which includes a plurality of spaced apartstationary transmitters each generating relatively short range, highlydirectional beam signals to a plurality of mobile receivers forreceiving the beam signals. The stationary transmitters include atransmitter means for transmitting a burst data stream signal, atransmitter antenna means connected to the transmitter means fortransmitting the beam signal in response to the burst data streamsignal, a transmitter control means connected to the transmitter meansand a transmitter memory means connected to the transmitter controlmeans for storing a plurality of compressed data voice messages. Thetransmitter control means selectively reads the messages from thetransmitter memory means and generates the messages as data packetsignals in a predetermined sequence in the burst data stream signal. Atraffic signal means can be connected to the transmitter control meansfor generating traffic signal state signals wherein the transmittercontrol means responds to the traffic signal state signals to generatestatus flag signals in the burst data stream signal. The mobilereceivers include a receiver antenna means for receiving the beamsignal, a mobile receiver means connected to the receiver antenna meansfor separating the burst data stream signal from the beam signal, areceiver control means connected to the mobile receiver means forreading the data packet signals from the mobile receiver means, a datadecompression means connected to the receiver control means fordecompressing the data packet signals, a receiver memory means connectedto the data decompression circuit and to the receiver control means forstoring the messages in decompressed form and an audio playback deviceconnected to the receiver control means for audibly reproducing themessages.

The burst data stream signal is generated as a serial string ofpredetermined length information windows, each window having an initialportion containing one of the status flag signals and a subsequentportion for containing a selected one of the data packet signals. Thereceiver control means responds to the status flag signals by generatinga traffic signal state indication from an output means connected to thereceiver control means.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention, willbecome readily apparent to those skilled in the art from the followingdetailed description of a preferred embodiment when considered in thelight of the accompanying drawings in which:

FIG. 1 is a wave form diagram of signals generated by an annunciatorsystem in accordance with the present invention;

FIG. 2 is a schematic view of an annunciator system according to thepresent invention utilized to convey traffic information; and

FIG. 3 is a detailed schematic block diagram of the annunciator systemshown in the FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention solves the receiver "residence time" problem byoperating the transmitter in a "burst mode". Such operation allows thetransmitter to transmit time compressed voice signals to a specialreceiver. The receiver demodulates this compressed voice data and storesit in a digital memory for later playback at normal rates. Note thatsuch a system does not operate in real time, but delivers the messagesome time after it was transmitted. This signal processing delay may bevery short and in virtually all cases is not very important.

Modern speech processing circuits and in particular ASICs (applicationspecific integrated circuits) for speech recording and playback allowsuch burst communication protocols to be implemented at very low cost.Advances in speech compression, and in linear predictive coding, permitthe digitized speech message to be broadcast over a relatively narrowbandwidth. For example, modern digital speech codecs (coders--decoders)are able to convey high quality speech with a digitizing rate of only 7KHz, which is amazing considering that telephone voice grade linesexhibit an analog bandwidth of less than 4 KHz. The importance ofconserving bandwidth is evident when time compressed or burst modetransmission is needed to convey relatively long messages in short timeintervals.

While digital data burst mode communication is common, thetime-compressed transmission of voice messages has not been practicaluntil the advent of advanced speech processing integrated circuits andlow cost playback devices. A digital, burst mode, voice messaging systemwould operate on the following principle: A voice message of 10 seconds(for purposes of illustration) would be compressed, digitized and storedin a solid state memory (EPROM or OTP etc.). This message would alsotypically be annotated with coded precursors and suffixes that identifythe message, the type of message, the length of message and otherutility functions.

At the transmitter, the digital data from the storage device would bebroadcast in burst mode by clocking the data out of the memory at asubstantially higher rate than the baseband (voice) signal was recorded.For example, the 7 KHz (more accurately 7 Kbps) rate of recording couldbe broadcast at 70 Kbps or even 140 Kbps, so that a 10 second messagewould be broadcast in 1 second or even 0.5 seconds of actualtransmission time.

At the receiver, the digital data would be stored in solid state memoryfor later playback. As the data is clocked out of the storage I.C., at arelatively slow rate, it is converted back to an analog signal that mayconvey an audible message. Depending upon the type or nature of themessage, as annotated by specific codes, the received data may be eitherstored for later playback or be converted immediately into an audiblemessage or alarm. In fact, the use of a number of "mail boxes" in thereceiver would allow various types of messages to be stored in separateregisters (memory) so that the user could selectively access thesemessages at will.

For example, emergency messages would be coded with specific precursorsor suffixes to direct them to channel 0 for immediate playback, whiletourist information would be stored in channel 1, navigation ordirectional information in channel 2, commercial (advertising) inchannel 3, etc. At the users' option, any or all of the memory channels(mail boxes) may be accessed as received or at a later time (except, ofcourse channel 0). Each channel or mail box could store any number ofmessages, which, unless purposely erased, would eventually beoverwritten by the most recent messages.

While the primary function of the burst communication system describedhere is the delivery of audible messages, digital data or alphanumericinformation could also be transmitted to appropriate receivers. Acombination of voice messages and alphanumeric data would be of value todrivers if a telephone number was transmitted for example. The wideproliferation of mobile telephones would allow drivers to call ahead forrestaurant or lodging reservations without having to write down orremember broadcast telephone numbers. A scrolling display on thereceiver could be used as an electronic (self registering) notepad.

Another application of the burst annunciator system according to thepresent invention might be to immediately advise speeding motorists oftheir actual speed, which might cause them to slow down. An active,short range Doppler radar or time of flight laser speed sensing device(Lidar) would be coupled to a voice messaging unit. Such devices wouldbe particularly useful in school zones, neighborhoods with special needs(deaf children) or similarly challenging safety zones. The utility ofthe burst communication as described for traffic advisory use would begreatly enhanced by the addition of "real time" markers to thecompressed data stream.

As explained above, many messages (particularly those of a commercialnature) may be delayed seconds or even tens of minutes with little lossof utility. However, certain traffic information needs to be relayedimmediately such as the actual disposition of a traffic control device.For example, red lights would have to be announced immediately, as wouldyellow and green signals, as well as railway crossing signals. As shownin the FIG. 1, the apparently incompatible demands for such a mixedsystem could be easily accommodated by recurring real time "flags"interspersed in the burst data stream. The periodic interval of thesestatus flags would be short enough to provide essentially a real timerelay of important signals, and to simultaneously permit thetransmission of relatively long messages for subsequent playback.

For example, as shown in a middle portion of the FIG. 1, a burst datastream signal 10 can be transmitted at 100 KHz which provides a streamor serial string of information windows each 100 msec long. A firstinformation window 12 contains a first status flag signal 14 in aninitial portion thereof followed by a first data packet signal 16 in asubsequent portion thereof. The first data packet signal 16 can containa compressed voice message of any type such as a code 0 (emergencymessage) identified by a precursor and/or suffix. A second informationwindow 18 follows the first window 12 and contains a status flag signal14 in an initial portion thereof followed by a second data packet signal20 in a subsequent portion thereof. The second data packet signal 20 cancontain a compressed voice message of any type such as a code 2(navigation message). Thus, status flag signals can be transmitted every100 msec in the reserved initial portion of each window. The periodictransmission of status flags would insure that the reception ofimportant signals would be no further than 100 msec away from the time areceiver begins to receive the transmitted signal containing the burstdata stream 10.

Note that during the transmission of relatively long messages, themessage may be split between two or more data packets. If the navigationmessage is relatively long, a first part may be included in the seconddata packet signal 20 and a second part included in a third data packet22 contained in a third information window 24. The status flag signals14 represent a monitored parameter of interest to the person receivingthe burst data stream 10. There is shown above the wave form 10, a plot26 of the state of a traffic signal associated with the transmittergenerating the burst data stream. Thus, the status flag signal 14 canrepresent a yellow light state of the traffic signal. During a longvoice message spanning at least two windows, the status flags couldchange reflecting a change in the monitored parameter. As shown, thestate of the traffic signal changes from yellow to red at approximatelythe end of the second window 18. Accordingly, a second status flagsignal 28 is generated in the initial portion of the third window 24representing the red light state of the associated traffic signal. Thesecond status flag signal 28 is generated again in the initial portionof a fourth information window 30 indicating that the traffic signal isstill red. The fourth information window 30 is shown as not containing adata packet signal which represents a situation wherein no message is tobe transmitted to the receiver or a window reserved only for code 0emergency messages.

There is shown below the burst data stream signal wave form 10 a plot 32of the response of a mobile receiver to the data packet signals 16, 20and 22 and to the status flag signals 14 and 28. During the firstinformation window 12, the receiver receives the first data packetsignal 16. A control associated with the receiver recognizes that thefirst data packet signal 16 is a code 0 emergency message and,therefore, decodes and plays back the voice message immediately whilethe subsequent data packet signals 20 and 22 are being received. Whilethe first data packet signal 16 is being processed, the second datapacket 20, the third data packet 22 and any other data packets which arereceived are stored in a memory for later playback. The control alsorecognizes the second status flag signal 28 and responds by generating ared light alert signal 34 which can be utilized to generate a visualand/or an audio output to warn the person adjacent the mobile receiverof the changed status of the traffic signal.

A system such as that described above could be applied to pedestriansignals that also announce their location or provide pertinent touristinformation. Portable receivers could be provided to visually impairedpedestrians as a mobility aid. Such a carried data receiver wouldrespond immediately to the change in "walk" or "don't walk" signals, butcould generate a compressed voice message for later playback.

Unimportant messages would be preempted by critical (safety) messages sothat the user could respond instantly to such announcements. Thepreemption of commercial or less important messages is only temporary asthe burst (voice) message is stored in digital memory and can be playedback at anytime until it is purposely erased.

There is shown in the FIG. 2 a schematic view of an annunciator systemaccording to the present invention utilized to provide trafficinformation to mobile receivers. First and second traffic signals 36 and38 respectively are spaced apart along a roadway 40. The first trafficsignal 36 is connected to a first stationary transmitter 42 (TX #1)which broadcasts a relatively short range, highly directional beamsignal 44 extending between a leading edge 44a directed toward the rightand a trailing edge 44b directed downwardly. Thus, the beam 44 isdirected toward receivers approaching the first traffic signal 36 fromthe right. The second traffic signal 38 is connected to a secondstationary transmitter 46 (TX #2) which generates a relatively shortrange, highly directional beam signal 48 extending between a leadingedge 48a directed toward the right and a trailing edge 48b directeddownwardly. Thus, the beam 48 is directed toward mobile receiversapproaching the second traffic signal 38 from the right. Typically, thebeams 44 and 48 do not overlap so that a moving receiver is not confusedby conflicting messages from two different transmitters.

A first mobile receiver 50 (RC #1) has passed through both of the beams44 and 48 and is positioned to the left of the trailing edge 48b. Thus,the first receiver 50 is not receiving any messages. A second mobilereceiver 52 (RC #2) has passed through the first beam 44 and ispositioned in the second beam 48 to receive messages being broadcast bythe second transmitter 46 including status flag signals representing thestatus of the second traffic signal 38. A third mobile receiver 54 (RC#3) is positioned in the first beam 44 to receive messages beingbroadcast by the first transmitter 42 including status flag signalsrepresenting the status of the first traffic signal 36. As shown in theFIG. 2, the beam signals 44 and 48 can be directed to portable receiverswhich are positioned within a predetermined area adjacent thetransmitters 42 and 46 respectively to selectively provide messages tosuch receivers.

There is shown in the FIG. 3 a schematic block diagram of a portion ofthe annunciator system shown in the FIG. 2. The first transmitter 42includes a first transmitter means 42a having an output connected to atransmitter antenna 56 for transmitting the first beam signal 44 to areceiving antenna 58 connected to an input of a third receiver means 54ain the third receiver 54. The transmitter 42a has an input connected toan output of a transmitter control 60 which generates the burst datastream 10 containing the status flag signals and the data packet signalsto modulate the carrier signal generated by the transmitter. Thetransmitter control 60 has an input connected to an output of the firsttraffic signal 36 for receiving a signal representing the traffic signalstate. The transmitter control 60 responds to the traffic signal statesignal by generating the status flag signals 14 and 28 as shown in burstdata stream 10 of the FIG. 1.

A first input/output of the transmitter control 60 is connected to aninput/output of a data compression circuit 62. The circuit 62 has aninput connected to an output of a analog/digital converter 64 which hasan input connected to an output of a voice input device 66. The voiceinput device 66 can be any device which converts sound waves into ananalog electrical signal such as a microphone. The converter 64 respondsto the analog signal by generating a digital signal representing theaudio information in the analog signal. The data compression circuit 62,under the direction of the transmitter control 60, compresses the datain the digital signal and the compressed data is read by the transmittercontrol 60. A second input/output of the transmitter control 60 isconnected to an input/output of a transmitter memory 68. The control 60sends the compressed data received from the data compression circuit 62and the traffic signal state signal received from the traffic signal 36to the memory 68 for storage therein. The transmitter control 60 thenutilizes the information stored in the transmitter memory 68 to form theburst data stream 10 shown in the FIG. 1.

The third receiver means 54a has an output connected to an input of areceiver control 70. The receiver 54a demodulates the burst data stream10 containing the status flag signals and the data packet signals fromthe carrier signal generated by the first transmitter 42a. The receivercontrol 70 has a first output connected to an input of a datadecompression circuit 72 and reads the data packet signals from thereceiver 54a to the data decompression circuit for decompressing thecompressed data. The circuit 72 has an output connected to an input of areceiver memory 74 wherein the status flag signals and the decompresseddata packet messages are then stored. The receiver control 70 has aninput/output connected to an input/output of the receiver memory 74 forreading the stored status flag signals and message data. The receivercontrol has a second output connected to an input of a digital/analogconverter 76 which changes the digital data from the receiver control 70into analog electrical signals at an output connected to an input of anaudio playback device 78. Thus, the voice messages sent by thetransmitter 42 can be heard by a person utilizing the receiver 54. Athird output of the receiver control 70 is connected to an input ofother output devices 78 which can be, for example, lights correspondingto the traffic signal lights and actuated by the red light alert signal34 shown in the FIG. 1. Although the data compression circuit 72 isshown as being connected between the receiver control 70 and thereceiver memory 74, the messages can be stored in compressed form andsent through the circuit 72 to the digital/analog converter 76 to beannunciated.

Prior to installation of the annunciator system according to the presentinvention, the voice input device 66, the analog/digital converter 64and the data compression circuit 62 are utilized to create apredetermined set of messages which are stored in the transmitter memory68. This operation can be performed with the transmitter control 60, orwith a computer connected between the circuit 62 and the memory 68. Forexample, a personal computer equipped with a Blaster® AWE32™ audio cardand microphone available from Creative Labs, Inc. of Milpitas, Calif.can be used to create the messages. Then the first transmitter 42, thetransmitter antenna 56, the transmitter control 60 and the transmittermemory 68 are connected to the first traffic signal 36 at the locationof the traffic signal along the roadway. The transmitter control 60 isprogrammed to continuously generate the burst data stream 10 shown inthe FIG. 1 having a serial string of predetermined length informationwindows. The traffic signal 36 provides the traffic control with thetraffic signal state information necessary to generate the status flagsignals. The data packet signals can be generated in response todifferent stimuli. For example, the traffic signal 36 typically isconnected to a traffic controller which receives information from acentral source in order to properly sequence the traffic signals in agiven area for efficient traffic flow. Such a controller can sendcontrol signals through the traffic signal 36 to direct the transmittercontrol 60 to select one or more of the compressed voice messages storedin the transmitter memory 68 to be broadcast as the data packet signals.The control signals also can be broadcast to the transmitter control 60by connecting an input of the transmitter control to a suitable receiverand antenna. The transmitter control 60 can be preprogrammed tobroadcast each of the code 1 (tourist information), code 2 (navigationor directional information) and code 3 (commercial information) messagesin a predetermined cyclic sequence which can be interrupted by a code 0(emergency information) message which is inserted into the next windowgenerated in the burst data stream 10. Alternatively, the burst datastream 10 can be generated with periodic open windows 30 which arereserved for code 0 messages. Likewise, the receiver control 70 can bepreprogrammed to reproduce each of the code 1 (tourist information),code 2 (navigation or directional information) and code 3 (commercialinformation) messages stored in the receiver memory 74 at predeterminedintervals or selectively broadcast only messages of a selected one ofthe codes. In either case, the annunciation of the lower priority codemessages can be interrupted by a code 0 (emergency information) message.

In summary, a system for annunciating information to mobile receiversincludes a plurality of spaced apart stationary transmitters 42,46generating relatively short range, highly directional beam signals 44,48respectively to a plurality of mobile receivers 50,52,54 for receivingthe beam signals. At least one stationary transmitter 42 includes atransmitter means 42a for transmitting a burst data stream signal 10, atransmitter antenna means 56 connected to the transmitter means 42a fortransmitting the beam signal 44 in response to the burst data streamsignal 10, a transmitter control means 60 connected to the transmittermeans 42a and a transmitter memory means 68 connected to the transmittercontrol means 60 for storing a plurality of compressed data voicemessages whereby the transmitter control means selectively reads themessages from the transmitter memory means and generates the messages asdata packet signals 16,20,22 in a predetermined sequence in the burstdata stream signal 10. A traffic signal means 36 can be connected to thetransmitter control means 60 for generating traffic signal state signalswherein the transmitter control means responds to the traffic signalstate signals to generate status flag signals 14,28 in the burst datastream signal 10. At least one mobile receiver 54 includes a receiverantenna means 58 for receiving the beam signal 44, a mobile receivermeans 54a connected to the receiver antenna means 58 for separating theburst data stream signal 10 from the beam signal 44, a receiver controlmeans 70 connected to the mobile receiver means 54a for reading the datapacket signals 16,20,22 from the mobile receiver means, a datadecompression means 72 connected to the receiver control means 70 fordecompressing the data packet signals 16,20,22, a receiver memory means74 connected to the data decompression circuit 72 and to the receivercontrol means 70 for storing the messages in decompressed form and anaudio playback device 78 connected to the receiver control means 70 foraudibly reproducing the messages.

The burst data stream signal 10 is generated as a serial string ofpredetermined length information windows 12,18,24,30, each window havingan initial portion containing one of the status flag signals 14,28 and asubsequent portion for containing a selected one of the data packetsignals 16,20,22. The receiver control means 70 responds to the statusflag signals 14,28 by generating a traffic signal state indication froman output means 80 connected to the receiver control means.

The present invention also includes a method for annunciatinginformation to mobile receivers including the steps of: a. storing aplurality of compressed data voice messages in a transmitter memorymeans 68; b. generating a burst data stream signal 10 from a transmittermeans 42a; c. selectively reading one of the stored messages from thetransmitter memory means 68 and generating the one message as a datapacket signal 16,20,22 in the burst data stream signal 10; d.transmitting a relatively short range, highly directional beam signal 44from an antenna means 56 in response to the burst data stream signal 10;and e. receiving and decompressing the data packet signal 16,20,22 witha mobile receiver 54 entering the beam signal 44 for annunciating theone message. The method also includes a step of generating status flagsignals 14,28 in the burst data stream signal 10, the status flagsignals representing important information. The step b. is performed bygenerating the burst data stream signal 10 as a serial string ofpredetermined length information windows 12,18,24,30, each of thewindows having an initial portion for containing one of the status flagsignals 14,28 and a subsequent portion for containing a selected one ofthe data packet signals 16,20,22. The method includes repeating the stepc. for selected ones of the stored messages and coding the data packetsignals 16,20,22 according to a predetermined priority. The step e.includes selecting messages associated with the data packet signals16,20,22 having a predetermined code for annunciation and immediatelyannunciating messages associated with the data packet signals 16 havinga predetermined code.

In accordance with the provisions of the patent statutes, the presentinvention has been described in what is considered to represent itspreferred embodiment. However, it should be noted that the invention canbe practiced otherwise than as specifically illustrated and describedwithout departing from its spirit or scope.

What is claimed is:
 1. An apparatus for annunciating information tomobile receivers comprising:A control means (60) for generating aplurality of data packet signals (16,20,22) containing compressed datavoice messages and a code for each data packet signal (16,20 22); atransmitter means (42a) for transmitting said coded data packet signals(16,20, 22) in a burst data stream (10); a receiver (54) for receivingand decompressing the burst data stream (10); and a control means (70)for reading and separating the coded data packet signals (16,20,22)according to code and selectively annunciating messages of apredetermined code.
 2. A method for annunciating information to mobilereceivers comprising the steps of:a. generating a plurality of datapacket signals (16,20,22) containing compressed data voice messages; b.generating a code with each of said data packet signals (16,20,22); c.transmitting said coded data packet signals (16,20,22) in a burst datastream (10) from a transmitter (42a); d. receiving and decompressing theburst data stream (10); e. separating said coded data packet signals(16,20,22); and f. selectively annunciating messages of a predeterminedcode.
 3. An apparatus for annunciating information to mobile receiverscomprising:a transmitter means (42a) for generating a burst data streamsignal (10); an antenna means (56) connected to said transmitter means(42a) for transmitting a relatively short range, highly directional beamsignal (44) in response to said burst data stream signal (10); atransmitter control means (60) connected to said transmitter means(42a); and a transmitter memory means (68) connected to said transmittercontrol means (60) for storing a plurality of compressed data voicemessages whereby said transmitter control means selectively reads atleast one of said messages from said transmitter memory means andgenerates said one message as a data packet signal (16,20,22) in saidburst data stream signal (10), said data packet signal to be receivedand decompressed by a mobile receiver (54) entering said beam signal(44) for annunciating said one message; and wherein said messages arecoded as to priority and said transmitter control means (60) generates ahigher priority one of said messages as one data packet signal (16)before generating a lower priority one of said messages as another datapacket signal (20,22).
 4. The apparatus according to claim 3 wherein atleast another one of said messages is coded as a highest priorityemergency information message and said transmitter control means (60)generates each of said lower priority messages as said another datapacket signal (20,22) in a predetermined cyclic sequence and interruptssaid predetermined cyclic sequence with said one data packet signal(16).
 5. An apparatus for annunciating traffic information comprising:astationary transmitter means (42a) for generating a burst data streamsignal (10) at an output, a transmitter antenna means (56) connected tosaid output of said transmitter means (42a) for generating a relativelyshort range, highly directional beam signal (454) in response to saidburst data stream signal(10); a transmitter control means (60) connectedto said transmitter means (42a); a transmitter memory means (68)connected to said transmitter control means (60) for storing a pluralityof compressed data voice messages, at least one of said messagesrepresenting traffic information whereby said transmitter control meansreads said one message from said transmitter memory means and generatessaid one message as a data packet signal (16, 20,22) in said burst datastream signal (10); a receiver antenna means (58) for receiving saidbeam signal (44); a mobile receiver means (54a) having an inputconnected to said receiver antenna means (58) for separating said burstdata stream signal (10) from said beam signal (44); a receiver controlmeans (70) connected to said mobile receiver means (54a) for readingsaid data packet signal (16,20,22) from said mobile receiver means; adata decompression means (72) connected to said receiver control means(70 for receiving and decompressing said data packet signal (16,20,22);and an audio playback device (78) connected to said receiver controlmeans (70) for audibly reproducing said one message from saiddecompressed data packet signal (16,20,22), and wherein said messagesare coded as to priority and said transmitter control means (60)generates a higher priority of one of said messages as one data packetsignal (16) before generating a lower priority of one of said messagesas another data packet signal (20,22) and said receiver control means(70) sends said higher priority message associated with said one datapacket signal (16) to said audio playback means (78) before sending saidlower priority message associated with said another data packet signal(20,22) to said audio playback means.
 6. The apparatus according toclaim 5 including a receiver memory means (74) connected to said datadecompression circuit (72) and to said receiver control means (70) forstoring said one message in decompressed form.
 7. An apparatus forannunciating traffic information comprising:a stationary transmittermeans (42a) for generating a burst data stream signal (10) at an output:a transmitter antenna means (56) connected to said output of saidtransmitter means (42a) for generating a relatively short range, highlydirectional beam signal (454) in response to said burst data streamsignal(10); a transmitter control means (60) connected to saidtransmitter means (42a); a transmitter memory means (68) connected tosaid transmitter control means (60 for storing a plurality of compresseddata voice messages, at least one of said messages representing trafficinformation whereby said transmitter control means reads said onemessage from said transmitter memory means and generates said onemessage as a data packet signal (16, 20,22) in said burst data streamsignal (10); a receiver antenna means (58) for receiving said beamsignal (44); a mobile receiver means (54a) having an input connected tosaid receiver antenna means (58) for separating said burst data streamsignal (10) from said beam signal (44); a receiver control means (70)connected to said mobile receiver means (54a) for reading said datapacket signal (16,20,22) from said mobile receiver means; a datadecompression means (72) connected to said receiver control means (70)for receiving and decompressing said data packet signal (16,20,22); andan audio playback device (78) connected to said receiver control means(70) for audibly reproducing said one message from said decompresseddata packet signal (16,20,22); and a traffic signal means (36) connectedto said transmitter control means (60) for generating a traffic signalstate signal and wherein said transmitter control means responds to saidtraffic signal state signal to generate a status flag signal (14,28) insaid burst data stream signal (10) and said receiver control means (70)responds to said status flag signal by generating a traffic signal stateindication from an output means (80) connected to said receiver controlmeans.
 8. The apparatus according to claim 7 wherein said burst datastream signal (10) is generated as a serial string of predeterminedlength information windows (12,18,24,30), each said window having aninitial portion for containing said status flag signal (14,28) and asubsequent portion for containing said data packet signal (16,20,22). 9.A system for annunciating information to mobile receivers comprising:aplurality of spaced apart stationary transmitters (42,46) generatingrelatively short range, highly directional beam signals (44,48)respectively; at least one said stationary transmitter (42) including atransmitter means (42a) for transmitting a burst data stream signal(10), a transmitter antenna means (56) connected to said transmittermeans (42a) for transmitting said beam signal (44) in response to saidburst data stream signal (10), a transmitter control means (60)connected to said transmitter means (42a) and a transmitter memory means(68) connected to said transmitter control means (60) for storing aplurality of compressed data voice messages whereby said transmittercontrol means selectively reads said messages from said transmittermemory means and generates said messages as data packet signals(16,20,22) in a predetermined sequence in said burst data stream signal(10); a traffic signal means (36) connected to said transmitter controlmeans (60) for generating traffic signal state signals and wherein saidtransmitter control means responds to said traffic signal state signalsto generate status flag signals (14,28) in said burst data stream signal(10); a plurality of mobile receivers (50,52,54) for receiving said beamsignals (44,48); and at least one said mobile receiver (54) including areceiver antenna means (58) for receiving said beam signal (44), amobile receiver means (54a) connected to said receiver antenna means(58) for separating said burst data stream signal (10) from said beamsignal (44), a receiver control means (70) connected to said mobilereceiver means (54a) for reading said data packet signals (16,20,22)from said mobile receiver means, a data decompression means (72)connected to said receiver control means (70) for decompressing saiddata packet signals (16,20,22), a receiver memory means (74) connectedto said data decompression circuit (72) and to said receiver controlmeans (70) for storing said messages in decompressed form and an audioplayback device (78) connected to said receiver control means (70) foraudibly reproducing said messages.
 10. The system according to claim 9wherein said burst data stream signal (10) is generated as a serialstring of predetermined length information windows (12,18,24,30), eachsaid window having an initial portion for contains one of said statusflag signals (14,28) and a subsequent portion for containing a selectedone of said data packet signals (16,20,22).
 11. The apparatus accordingto claim 9, wherein said receiver control means (70) responds to saidstatus flag signals (14,28) by generating a traffic signal stateindication from an output means (80) connected to said receiver controlmeans.
 12. A method for annunciating information to mobile receiverscomprising the steps of:a. storing a plurality of compressed data voicemessages in a transmitter memory means (68); b. generating a burst datastream signal (10) from a transmitter means (42a); c. selectivelyreading one of the stored messages from the transmitter memory means(68) and venerating the one message as a data packet signal (16,20,22)in the burst data stream signal (10); d. transmitting a relatively shortrange, highly directional beam signal (44) from an antenna means (56) inresponse to the burst data stream signal (10); e. receiving anddecompressing the data packet signal (16,20,22) with a mobile receiver(54) entering the beam signal (44) for annunciating the one message; andf. generating status flag signals (14,28) in the burst data streamsignal (10), the status flag signals representing important information.13. The method according to claim 12 wherein said step b. is performedby generating the burst data stream signal (10) as a serial string ofpredetermined length information windows (12,18,24,30), each of thewindows having an initial portion for containing one of the status flagsignals (14,28) and a subsequent portion for containing a selected oneof the data packet signals (16,20,22).
 14. The method according to claim12 including repeating said step c. for selected ones of the storedmessages.
 15. A method for annunciating information to mobile receiverscomprising the steps of:a. storing a plurality of compressed data voicemessages in a transmitter memory means (68); b. generating a burst datastream signal (10) from a transmitter means (42a); c. selectivelyreading one of the stored messages from the transmitter memory means(68) and generating the one message as a data packet signal (16,20,22)in the burst data stream signal (10); d. transmitting a relatively shortrange, highly directional beam signal (44) from an antenna means (56) inresponse to the burst data stream signal (10); e. receiving anddecompressing the data packet signal (16,20,22) with a mobile receiver(54) entering the beam signal (44) for annunciating the one message; andf. coding the data packet signals (16,20,22) according to apredetermined priority.
 16. The method according to claim 15 whereinsaid step e. includes selecting messages associated with the data packetsignals (16,20,22) having a predetermined code for annunciation.
 17. Themethod according to claim 15 wherein said step e. includes immediatelyannunciating messages associated with the data packet signals (16)having a predetermined code.
 18. An apparatus for annunciatinginformation to mobile receivers comprising:a transmitter means (42a) forgenerating a burst data stream signal (10); an antenna means (56)connected to said transmitter means (42a) for transmitting a relativelyshort range, highly directional beam signal (44) in response to saidburst data stream signal (10); a transmitter control means (60)connected to said transmitter means (42a) and a transmitter memory means(68) connected to said transmitter control means (60) for storing aplurality of compressed data voice messages whereby said transmittercontrol means selectively reads at least one of said messages from saidtransmitter memory means and generates said one message as a data packetsignal (16,20,22) in said burst data stream signal (10), said datapacket signal to be received and decompressed by a mobile receiver (54)entering said beam signal (44) for annunciating said one message; andwherein said transmitter means (42a) generates said burst data streamsignal (10) as a serial string of predetermined length informationwindows (12,18,24,30) and said data packet signal (16,20,22) ispositioned in a selected one of said windows.
 19. The apparatusaccording to claim 18 including a traffic signal means (36) connected tosaid transmitter control means (60) for generating a traffic signalstate signal and wherein said transmitter control means responds to saidtraffic signal state signal to generate a status flag signal (14,28) ineach of said information windows (12,18,24,30).
 20. The apparatusaccording to claim 18 including voice input means (62,64,66) connectedto said transmitter memory means (68) for generating said compresseddata voice messages.
 21. The apparatus according to claim 20 whereinsaid voice input means (62,64,66) includes a voice input device (66)connected to an analog/digital converter (64) for converting sound intoa digital signal and a data compression circuit (62) connected betweensaid analog/digital converter (64) and said transmitter memory means(68) for generating said compressed data voice messages from saiddigital signal.
 22. An apparatus for annunciating information to mobilereceivers comprising:a transmitter means (42a) for generating a burstdata stream signal (10); an antenna means (56) connected to saidtransmitter means (42a) for transmitting a relatively short range,highly directional beam signal (44) in response to said burst datastream signal (10); a transmitter control means (60) connected to saidtransmitter means (42a); and a transmitter memory means (68) connectedto said transmitter control means (60) for storing a plurality ofcompressed data voice messages whereby said transmitter control meansselectively reads at least one of said messages from said transmittermemory means and generates said one message as a data packet signal(16,20,22) in said burst data stream signal (10), said data packetsignal to be received and decompressed by a mobile receiver (54)entering said beam signal (44) for annunciating said one message; and atraffic signal means (36) connected to said transmitter control means(60) for generating a traffic signal state signal and wherein saidtransmitter control means responds to said traffic signal state signalto generate a status flag signal (14,28) in said burst data streamsignal (10).
 23. The apparatus according to claim 22 including aplurality of mobile receivers (50,52,54) receiving and decompressingsaid data packet signal (16,20,22) upon entering said beam signal (44)for audibly reproducing said one message.
 24. The apparatus according toclaim 22 including a mobile receiver means (54a), a receiver antennameans (58) for receiving said beam signal (44) and being connected to aninput of said mobile receiver means, a data decompression means (72)connected to said mobile receiver means for decompressing said onemessage in said data packet signal (16,20,22), and an audio playbackdevice (78) connected to said data decompression means for audiblyreproducing said one message.
 25. The apparatus according to claim 24including a receiver memory means (74) connected between said datadecompression circuit (72) and said audio playback device (78) forstoring said one message in decompressed form.
 26. The apparatusaccording to claim 24 including a digital/analog converter means (76)connected between said data decompression circuit (72) and said audioplayback device (78) for converting said one message from digital formto analog form.